1. Field of the Invention
The present invention relates generally to a machining apparatus for performing repetitive machining operations on a workpiece, and more particularly, to a computer controlled machining apparatus and associated work table assembly. The invention also relates to an improved work table assembly for use with a computer controlled machining apparatus.
2. Description of the Prior Art
Machining apparatus, and more particularly, computer controlled machining apparatus or machining centers currently exist in the art. Such apparatus or machining centers are designed to perform repetitive machining operations on a workpiece supported by a work table. Examples include the computer controlled machining centers manufactured and sold by Komo Machine, Inc. of Sauk Rapids, Minn. under the trademarks VR508Q, VR805Q, and VR1005Q. Each of these machining centers includes a support base and a single work table mounted on the base to support the workpiece for reciprocal movement along the table movement axis. Each machining center also includes a machine carriage and a plurality of spindles or machine heads with mechanisms for moving the same along horizontal motion and vertical motion axes. Each machine head is provided with a work tool or bit to perform the desired machining operation on the workpiece.
Machining centers are also available in which the work table assembly includes a pair of independently moveable side-by-side work tables. One of these includes a single drive mechanism with a means in the form of a shear pin type arrangement for connecting the work tables to the drive mechanism. Most twin work table assemblies, however, embody a separate drive mechanism for each work table.
While the above described machining centers and associated work tables are satisfactory for many applications, various limitations exist. One limitation of single work table systems is the fact that significant down time exists during the time that finished workpieces are removed from the work table and replaced with new, unmachined workpieces. This downtime adversely affects the production capability or efficiency of the machining center, and thus the cost of the machined workpieces as well. Although this disadvantage can be overcome to some extent with the twin work table systems described above, disadvantages still exist. For example, for those systems embodying separate drive mechanisms for each work table, limitations include expense and system complexity. Further, difficulties arise when trying to synchronize movements of the two tables due to following error. For the system embodying a single drive mechanism, accuracy of work table alignment and positioning is a problem.
Accordingly, there is a need in the art for an improved computer controlled machining center and associated work table in which the down time resulting from workpiece changeover can be substantially reduced or eliminated and which is cost effective and provides for accurate work table alignment and positioning.